Traditional cable TV systems were little more than a wired medium for transport of the radio-frequency (RF) signal formerly carried over the air. Coaxial (coax) cables carried a set of all available broadcast channels to each TV (subscriber). A settop box in such a system simply provided an alternate tuner for receiving the additional channels available via the coax. Each settop box received the same array of channels via the analog signal carried on the coax.
In such legacy systems, selective services (i.e. “movie” channels such as HBO®) employed physical filters, usually on the cable drop to individual houses, to provide these premium services. With the advent of digital transport mediums, the same coax also carries digital signals. Modern settop boxes evolved to individually addressable network devices, so premium channels became switchable from a central office or headend. Selective viewing evolved to provide a greater granularity of control to individual settop boxes, allowing for video-on-demand (VOD) and switched digital video (SDV), thus enabling individual subscribers invoke programming selectively directed to their settop box. Such a greater granularity of control, as well as improvements in the viewable picture quality provided by Hi-Def (HD) formats, imposed a demand for greater bandwidth on the transport network. While advances in the physical transport network, such as fiber optic and higher frequency ranges, facilitated transport of this greater bandwidth, continuing advances in transport formats and user control place an additional burden on service providers to prudently and efficiently manage available bandwidth to effectively provide video services to a multitude of users.
A video service delivery environment provides video services, such as switched digital video (SDV) and video on demand (VOD) and continue to proliferate as the network infrastructure continues to evolve to support the bandwidth demands of applications providing selective services. Such a network infrastructure includes headends for providing video services, service nodes for executing applications for delivering the video services, and set-top boxes or other user device for rendering the service to users. The network arranges the set-top boxes into service groups, which are collections of set-top boxes served by a common set of connections emanating from the head end and terminating at the service groups. Typically, each of the set-top boxes is disposed in geographic proximity to others in the group, and the connections defined by physical sets of lines that branch out to the various service groups. While generally available programming (i.e. basic cable) is typically available to all set top boxes, in a so-called “broadcast” transmission, other services such as video-on-demand are sent to individual set-top boxes on “narrowcast” channels.